What ground game..you mean the weaseling he does after losing a primary election?
The Cruz supporters would be outraged if this happened with the General Election and the Electoral college just voted for whoever they wanted (whoever schmoozed them the best).
Here's the issue -- I think most of us agree that a rule requiring the nominee to gain a majority of votes is reasonable - that's sort of the basis of any democratic system. And given the very real possibility that a convention could begin with no candidate having a majority, the rules must permit delegates, at some point, to vote for someone other than the person to whom they were pledged. Otherwise, every ballot would have the exact same candidates getting the exact same votes, and nobody would ever get a majority.
I personally think the best rule is that delegates pledged to a candidate must continue to vote for that candidate on subsequent ballots as long as that candidate is one of the top two vote getters. There may even be states that have such a rule because those rules are set by each state's own party.
Best thing I could say is that if you want to have more of a voice in the delegate rules for your state, be more active in the party, and pay more attention to who gets appointed to the party's central committee. I'm not sure any other solution is really possible.